In the electrical discharge machining of a workpiece, electricity is typically conducted from the workpiece, through a dielectric fluid and to an electrode, in order to erode away material from the workpiece. Electrical discharge machining (EDM) is desired for the finished quality of the machined surfaces it produces and the high degree of precision made possible with this technique. However, depending on the amount of material being machined, and therefore removed, electrical discharge machining can take an undesirable length of time to complete an operation, such as drilling a hole. Such slow removal rates have limited the cost effectiveness of using EDM techniques in high volume manufacturing applications, especially where relatively large portions of a workpiece are being removed. In order to make electrical discharge machining techniques more cost effective, changes need to be made that will increase the machining rates attainable and improve the overall efficiency of the process, while still maintaining the surface quality and dimensional precision expected from an EDM process.
Therefore, there is a need for a more efficient electrical discharge machining apparatus and method capable of machining holes at faster rates than heretofore possible while maintaining high quality finished surfaces and a high degree of precision in the holes being machined.